The present invention relates generally to ultrasonic proximity switches for use with different types of sensors, and more particularly to an ultrasonic proximity switch with an oscillator which oscillates with an oscillator frequency.
In known ultrasonic proximity switches, the received echo is usually evaluated in separate evaluation electronics. To enable ultrasonic proximity switches to operate with different sensor designs, the evaluation parameters in the evaluation electronics must be adapted to the type of sensor being used. To avoid errors, the system is advantageously switched over automatically when a new sensor type is connected.
German Patent 34 28 773 discloses a method of sensor identification which is realized by coupling different voltage levels to a sensor output signal during exactly defined time spans. Other methods use manual coding. However, as more sensors are used and consequently have to be differentiated, these types of sensor identification become all the more costly and interference-prone.
The present invention is directed to the problem of developing an ultrasonic proximity switch, which is simple and reliable regarding the sensor recognition.